In recent years, along with the progress of miniaturization, increase of frequency and increase of electric current of an electric device and an electronic device, an inductance element is required to be dealt with similarly. However, in the current mainstream ferrite materials among a magnetic core which forms the inductance element, the material properties themselves are approaching the limit, and thus a new magnetic core material is being required. For example, ferrite materials are replaced with new materials such as Sendust and amorphous foil strip, however the replacement is adopted only in a part of the materials. An amorphous powder material having excellent magnetic properties is now known, however forming performance of the amorphous powder material is inferior compared to the conventional materials, and therefore the amorphous powder material is not used widely.
FIGS. 10(a) and 10(b) illustrate a conventional inductance element provided with at least two U-shaped magnetic cores or UU-shaped magnetic cores, and a coil wound around at least one portion of the magnetic cores. FIGS. 10(a) and 10(b) illustrate the inductance element provided with a UU-shaped core with a coil, and FIG. 10(a) is a plane view and FIG. 10(b) is an A-A cross-sectional view.
In an inductance element 13 shown in FIGS. 10(a) and 10(b), leg parts 15 of UU-shaped magnetic cores 14 are abutted to each other, and the magnetic cores 14 are housed in a resin case 16. Further, coils 17 are arranged at two portions of the leg parts 15. The resin case 16 is obtained by mutually fixing contact surfaces of an upper side upper face 16a, an upper side rear face 16b, a lower side upper face 16c and a lower side rear face 16d in the plane view formed separately as four members. Further, the coil 17 is usually assembled as a core member wound in advance when the core is fixed. FIGS. 11(a) to 11(c) illustrate a U-shaped magnetic core resin case, and FIG. 11(a) is a plane view, FIG. 11(b) is a front view and FIG. 11(c) is a rear view. A resin case 16′ is provided with an upper part 16′a and a rear face 16′b in the plane view.
In a normal U-shaped magnetic core in which soft magnetic plates such as amorphous foil strips are laminated, peripheries of cores are bound by a metal band or the like. However, when the coil member described above is assembled at the same time, binding processing using the band is apt to be complicated, and therefore automation of the binding processing is difficult. Further, when a dust magnetic core formed from magnetic powder material is fixed by the metal band, high radial crushing strength and a lower rattler value are required, and therefore application of this method is limited. Further, even if the dust magnetic core is not fixed by the metal band or the like, a jig for holding the U-shaped magnetic cores to be fixed by an adhesive while positioning the U-shaped magnetic cores is necessary, and therefore assembling processing becomes complicated.
As a reactor using divided magnetic cores, a reactor provided with lamination cores arranged in a square shape, a coil wound around the lamination core which forms a side surface and is arranged to be perpendicular to each outer lamination core via an insulation spacer for forming a gap, and a bobbin with an insulating cylindrical shape in which the lamination core forming the side surface is arranged, is known (see Patent Document 1). In the reactor, the lamination core arranged in the bobbin is divided into two cores in an axial direction, and a partition wall for forming a gap between divided cores is formed integrally with an inner wall part of the bobbin. Further, a reactor provided with a core unit formed by continuously arranging first cores with at least one gap, each of the first cores has a plurality of magnetic properties; a reactor core with a substantially ring shape in a plane view formed by arranging two core units to face each other and arranging second cores having a magnetic property between end parts of the two core units so as to face each other with a predetermined gap; and a fixing member which holds and fixes the position of the first cores forming the core unit and the position of the two second cores, the fixing member being fixed to a case via an elastic body, is known (see Patent Document 2).